The present invention relates to a light detection device for indicating whether faint characteristic return light is emitted from a test sample irradiated with excitation light.
A typical light detection device irradiates a test sample with excitation light and detects characteristic return light (luminescence, fluorescence, reflected light, scattered light) included in the return light from the test sample to analyze the test sample.
In a light detection device such as a fluorescence microscope or a microplate reader, test samples are accommodated in a plurality of wells formed on a microplate. A conventional light detection device irradiates the entire microplate with excitation light having a specific wavelength to generate an image of the entire surface of the microplate with an imaging device such as a charge-coupled device (CCD) camera. The light detection device performs image processing on a picture image or image data of a plurality of light emitting points (characteristic return light) on the microplate to display an image.
Japanese National Phase Laid-Open Publication No. 2001-505654 describes a light detection device including an integrated cooled CCD camera, an image processing computer, and a display. The integrated cooled CCD camera is arranged at an observing position in a fluorescence microscope optical system to generate an image of the entire microplate. The image data of the entire microplate generated by the CCD camera is retrieved in the computer and shown on the display. This type of light detection device is designed for use in, for example, a large inspection room to perform measurement on a large quantity of microplates, which conform to predetermined standards.
An operator using such a light detection device is unable to determine whether or not light having a wavelength differing from that of the excitation light, that is, characteristic return light such as fluorescence, has been emitted from the test sample until the image data of the microplate is processed by the computer and displayed on the display. The conventional light detection device is thus complicated, large, expensive, and difficult to carry. Moreover, it is difficult for the operator to determine whether characteristic return light is emitted from each test sample on the microplate by looking at the test samples.